Polyvinylidene fluoride and polyvinylidene fluoride type copolymers are known to be used as piezoelectric materials and pyroelectric materials. For example, Japanese Unexamined Patent Application 2010-108490 mentions a transparent piezoelectric sheet containing a vinylidene fluoride-tetrafluoroethylene copolymer, and also mentions using this sheet as a touch panel. Furthermore, Japanese Unexamined Patent Application 2011-222679 discloses a vinylidene fluoride-tetrafluoroethylene copolymer, a vinylidene fluoride-trifluorethylene copolymer, and use of polyvinylidene fluoride as a transparent piezoelectric film material for a transparent piezoelectric.
On the other hand, a method in which polyhedral oligomeric silsesquioxane (POSS) synthesized in advance or polyhedral oligomeric silicate is added to a fluoropolymer is known as a method for improving thermal properties and mechanical properties of fluoropolymers such as polyvinylidene fluoride or the like. Furthermore, a composite material provided by blending fluorinated POSS in polyvinylidene fluoride using a twin screw extruder is known (U.S. Pat. No. 7,193,015).
Furthermore, a method that crosslinks a vinyl group-containing polyhedral oligomeric silsesquioxane by a hydrosilylation reaction using a crosslinking agent having a silicon atom bonded hydrogen atom for a fluoropolymer blended with a vinyl group-containing polyhedral oligomeric silsesquioxane, and a composite material obtained using the method are known. Furthermore, it is known that the alkyl group of the polyhedral oligomeric silsesquioxane (POSS) can contain a fluorinated group (U.S. Pat. No. 7,553,904).
Furthermore, a piezoelectric polymer blend containing a piezoelectric polymer and a matrix polymer is also known (U.S. Patent Application No. 2014/0117272). In this application, polyvinylidene fluoride, polyvinylidene fluorine-trifluoroethylene, and the like in addition to poly (γ-benzyl-α, L-glutamate) are mentioned as the piezoelectric polymer, and polymethyl methacrylate, polyethylene, polyvinyl chloride, poly (1-butene), silicone elastomer, silicone rubber, and the like are mentioned as the matrix polymer. However, a polymer blend in which polyvinylidene fluoride is combined with organopolysiloxane having a fluorine-containing organic group is not mentioned. Furthermore, there is no mention or suggestion for a substantially transparent composite material made by dispersing fluoropolymers such as polyvinylidene fluoride or the like with an organopolysiloxane crosslinking reaction product having a fluorine-containing organic group in an integral and mutually inseparable condition.